[patch, fortran, 4.9] Improve efficiency of array constructor operators

[Thomas Koenig]

Hi Tobias,

I have committed the two approved patches, with the issues that you
have noted fixed.

Thanks a lot for the reviews!

> PS: Regarding the string comparison patch: As Janne, think it should be
> fine with also supporting kind=4 (don't forget to multiply the length by
> the kind, e.g. ts.kind or more properly (but equivalently)
> gfc_character_kinds[<index>].bit_size/BITS_PER_BYTE).

I'll do that.

> As follow up, I think you could do what Ondřej suggested.

I will also take a look at that.

Regards

	Thomas